diff --git a/tests/test_encoding_helpers.py b/tests/test_encoding_helpers.py
index 7efb72c4..bfe2f096 100644
--- a/tests/test_encoding_helpers.py
+++ b/tests/test_encoding_helpers.py
@@ -125,7 +125,8 @@ def test_prefix_file_wrapper(factory):
     assert f.read() == b"abcdef"
 
     f = feedparser.encodings.PrefixFileWrapper(b"abc", factory(b"def"))
-    assert f.read(2) == b"ab"
+    assert f.read(1) == b"a"
+    assert f.read(1) == b"b"
     assert f.read() == b"cdef"